How to call a Python function that returns multiple values with Python Interface

I have a Python function that returns multiple values. How can I call my Python function to return multiple values?

 

Answer 1

[MathWorks Support Team]

When a Python function returns multiple values, these values will be returned to MATLAB as a single Python tuple object. To retrieve individual values, you will need to unwrap the tuple. This can be illustrated with the Python code below.

# WordCount.py
def CountWords(text):
    # remove spaces
    text = text.strip()
    # remove punctuation
    text = text.translate({ord(i): None for i in ',.;\/!?-_`|><'})
    # convert to lowercase
    text = text.lower()
    word = text.split()
    return len(word), word

The "CountWords" function takes a string as an input argument, removes punctuation, converts to lowercase, and returns the number of words and a list of the words. The following steps show how to call the function and access the individual return values.

Create a string

>> s="The cow jumped over the moon.";

Call the Python function with a single return variable "pyvals".

>> pyvals = py.WordCount.CountWords(s)

pyvals = 

  Python tuple with values:

    (6, ['the', 'cow', 'jumped', 'over', 'the', 'moon'])

    Use string, double or cell function to convert to a MATLAB array.

The word count (6) and the list of words are contained in the tuple. Convert the tuple to a MATLAB cell array

>> mlvals = cell(pyvals)

mlvals =

  1×2 cell array

    {1×1 py.int}    {1×6 py.list}

Now extract the individual return values. Convert the word count to a MATLAB int32  value.

>> numWords = int32(mlvals{1})

numWords =

  int32

   6

Convert the list of words to a MATLAB string array.

>> Words = string(mlvals{2})

Words = 

  1×6 string array

    "the"    "cow"    "jumped"    "over"    "the"    "moon"